It could be outside the light cone, say.

If the computer doesn't know it's outside of the lightcone, that's irrelevant. The room may not even exist, but as long as the computer doesn't know that, it can't eliminate the possibility that it's in that room.

but it's low enough that even the favorable likelihood ratio of the subsequent evidence is insufficient to raise the hypothesis to serious consideration.

The probability of it being that specific room is far too low to be raised to serious consideration. That said, the utility function of the computer is such that that room or anything even vaguely similar will matter just about as much.

Do you agree that if the teenager's computer were not receiving input from the sensors, it would be inaccurate to say it has evidence about the room's temperature?

Only if the computer knows it's not receiving input from the sensors.

It has no evidence of the temperature of the room given that it's not receiving input from the sensors, but it does have evidence of the temperature of the room given that it is receiving input from the sensors, and the probability that it's receiving input from the sensors is finite (it isn't, but it doesn't know that), so it ends up with evidence of the temperature of the room.